As is well known to those skilled in the art, printing plates of the aforesaid type must be periodically cleaned in order to maintain satisfactory printing quality. Such cleaning is now customarily performed either by hand or by an apparatus having a plate supporting frame upon which the plates to be cleaned are placed in a semi-flattened condition. The apparatus further includes a reciprocating spray assembly that sprays water or other cleaning fluid downwardly upon the plates upon the bed as the assembly reciprocates to and fro above them. The aforesaid apparatus does not always clean the plates as rapidly or thoroughly as desired. Most importantly, deforming of the plates to a flattened condition during cleaning significantly decreases their useful life.
Other apparatuses previously used primarily for etching, but in some cases also for washing, arcuate printing plates include elongate rotatable cylinders or drums upon which the plates are mounted. These apparatuses impose less bending stress upon the plates during mounting and customarily include one or more spray assemblies that direct water or other cleaning fluid onto the plates mounted upon and rotatable in unison with the drums. The apparatuses may include a brush that also engages the rotating plate for the purpose of assisting in their cleaning. Prior U.S. patents disclosing apparatuses of the foregoing general type include U.S. Pat. Nos. 4,090,907, 3,573,119, 3,323,528 and 3,088,391. Other prior U.S. patents of possible interest relative to the present invention include U.S. Pat. Nos. 4,842,001, 3,479,222, 3,442,251, 3,141,467 and 1,106,795.